1. Field of the Invention
This invention relates to an apparatus for cooling the heat exchanger of an air conditioning condenser unit and more particularly to an apparatus for applying a cooling water spray to the heat exchanger of an air conditioning condenser unit.
2. Information Disclosure Statement
Air conditioning systems, both for residential and commercial use, are often installed with a condenser unit which uses the atmosphere as a heat sink. The condenser unit is generally mounted outside the structure enclosing the space to be air conditioned. Typical locations for the condenser unit are at ground level just outside the structure to be air conditioned, or on the roof of the structure.
In the condenser unit of typical installations, a compressor operates periodically under the control of a thermostat (located in the air conditioned space) to pump a hot refrigerant gas through a heat exchanger where the gas gives up its thermal energy to the atmosphere. This is accomplished by drawing air through the heat exchanger, thus heating the air and cooling the refrigerant gas to below its boiling point at the operating pressure of the system.
As the heat load upon the system increases, the compressor tends to run for longer intervals of time, and the "OFF" periods are of increasingly shorter duration. Wear in the system, particularly in the compressor, is increased, power consumption is dramatically increased, and overall system efficiency generally decreases under such conditions.
Additional cooling capacity in the condenser unit heat exchanger can be of substantial benefit during periods of a high heat load on the system, and may also provide energy consumption benefits in general even where the heat load is not exceptionally high. Means for providing additional cooling to the condenser unit heat exchanger have often involved the use of water for cooling purposes in the prior art. One method employed in the prior art was to drip water onto the heat exchanger cooling fins, where it would generally run down the vertical fins and hopefully wet the fin surface, thus providing both evaporative and conductive cooling for the heat exchanger.
Another water cooling method in the prior art is described in U.S. Pat. Nos. 4,170,117 and 4,240,265. This method uses a water spray directed at the air intake side of the condenser unit heat exchanger. The advantage of this method is that better dispersion of the cooling water is achieved, thus making better use of the cooling medium throughout the intake area of the heat exchanger. A further refinement discribed in the above-mentioned patents is the control of the water spray so that it is generally shut off when the system is not in operation. As described in the above-mentioned patents, this control is accomplished by use of a thermal sensor placed in contact with the heat exchanger of the condenser unit. In the prior art systems, this thermal sensor may or may not be within the spray pattern of the cooling water spray.
A significant disadvantage of the thermally-controlled spray system is that it tends to cause excessive amounts of water to be applied for excessive amounts of time to the heat exchanger, with the result that the heat exchanger is continually wet during operation. Excess water generally collects near the bottom of the heat exchanger, resulting in such problems as growth of fungus and flooding. Such excess water can also encourage the growth of excessive amounts of vegetation in cases where the condenser unit is installed at ground level, and such vegetation can tend to interfere with air flow into the intake side of the heat exchanger. In rooftop installations, the more or less continual flooding can cause problems with the roof covering material. Excessive corrosion of metallic parts and deposit of scale are also significant problems in these prior systems.
These problems exist even in the systems employing thermal control of the water flow, since the heat exchanger can remain sufficiently hot for a period of time after the shutdown of the compressor for the system to continue supplying water which is not actually needed for cooling purposes at that time. Further, the location of a thermal sensor in the heat exchanger itself for providing control of the flow of water can often result in the sensing of incorrect apparent conditions if the cooling water spray can affect the thermal sensor. Even if the thermal sensor is located outside of the normal spray pattern for the cooling water spray, varying wind conditions can cause the spray to be blown into the area of the heat exchanger which houses the thermal sensor, thus creating different ambient conditions and causing incorrect operation of the system.
The above disadvantages of flooding and applying excessive water in general to the heat exchanger of the condenser unit apply equally to the "drip" systems mentioned above, of course.
Therefore, it is an object of this invention to provide an apparatus which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the pertinent art.
Another object of this invention is to provide an apparatus for applying a cooling water spray to the heat exchanger of an air conditioning condenser unit, a solenoid valve for controlling water flow, a spray nozzle for creating and directing the cooling water spray onto the heat exchanger, and a control unit for controlling the solenoid valve.
Another object of this invention is to provide an apparatus for applying a cooling water spray to the heat exchanger of an air conditioning condenser unit as described above which includes a water filter with a replaceable filter element in order to filter the water prior to applying it as a cooling water spray to the heat exchanger.
Another object of this invention is to provide an apparatus for applying a cooling water spray to the heat exchanger of an air conditioning condenser unit as described above which includes a water filter which includes water softening means for removing scale-forming ions from the water prior to applying it as a cooling spray to the heat exchanger.
Another object of this invention is to provide an apparatus for applying a cooling water spray to the heat exchanger of an air conditioning condenser unit as outlined above in which the cooling water spray may be applied to the heat exchanger only when the heat exchanger is actually in operation.
Another object of this invention is to provide an apparatus for applying a cooling water spray to the heat exchanger of an air conditioning condenser unit, including a solenoid valve, a spray nozzle and a control unit as described above, wherein the control unit is merely a very low frequency oscillator with its "OFF" and "ON" period being independently selectable.
Another object of this invention is to provide an apparatus for applying a cooling water spray to the heat exchanger of an air conditioning condenser unit as described above, in which a sacrificial anode is installed in contact with the heat exchanger in order to minimize the above-mentioned problems of corrosion which are typical in systems of this type.
Other objects and a fuller understanding of this invention may be had by referring to the summary of the invention, the description and the claims, taken in conjunction with the accompanying drawings.